Carrier Transport mechanisms contributing to the sub-threshold current in 3C-SiC-on-Si Schottky Barrier Diodes

3C-Silicon Carbide (3C-SiC) Schottky Barrier Diodes on silicon (Si) substrates (3C-SiC-on-Si) seem not to comply with the superior wide band gap expectations in terms of excessive measured sub-threshold current. In turn, that is one of the factors which deters their commercialization. Interestingly, the forward biased part of the Current-Voltage (I-V) characteristics in these devices carries considerable information about the material quality. In this context, an advanced Technology Computer Aided Design (TCAD) model for a vertical Platinum/3C-SiC Schottky power diode is created and validated with measured data. The model includes defects originating from both the Schottky contact and the hetero-interface of 3C-SiC with Si which allows the investigation of their impact on the magnification of the sub-threshold current. For this, barrier lowering, quantum field emission and trap assisted tunneling of majority carriers need to be considered at the non-ideal Schottky interface. The simulation results and measured data allowed for the comprehensive characterization of the defects affecting the carrier transport mechanisms of the forward biased 3C-SiC on Si power rectifier for the first time

Experimental and physics based study of the Schottky Barrier Height inhomogeneity and associated traps affecting 3C-SiC-on-Si Schottky Barrier Diodes

The ability of cubic phase (3C-) Silicon Carbide (SiC) to grow heteroepitaxially on Silicon (Si) substrates (3C-SiC-on-Si) is an enabling feature for cost-effective Wide Bandgap devices and homogeneous integration with Si devices. In this paper, the authors evaluated 3C-SiC-on-Si Schottky Barrier Contacts by fabricating and testing non-freestanding lateral Schottky Barrier Diodes (LSBD). To gain a deep physical insight of the complex carrier transport phenomena that take place in this material, advanced Technology Computer Aided Design (TCAD) models were developed which allowed accurately matching of measurements with simulations. The models incorporate the device geometry, an accurate representation of the bulk material properties, and complex trapping/de-trapping and tunnelling phenomena which appear to affect the device performance. The observed non-uniformities of the Schottky Barrier Height (SBH) were successfully modelled through the incorporation of interfacial traps. The combination of TCAD with fabrication and measurements enabled the identification of trap profiles and pin their influence on the electrical performance of 3C-SiC-on-Si LSBD. The effect of temperature was studied by engaging the identified trap profiles and calculating the occupation distribution of electrons in 3C-SiC at elevated temperature. The investigation constitutes an imperative knowledge step towards the development of devices that take advantage of 3C-SiC material properties

Welcome [by J.H.H. Weiler, Dario Nardella, Konstantinos Arvanitopoulos]

This contribution was delivered on the occasion of the EUI State of the Union in Florence on 9 May 2014

Hybrid Silica Xerogel and Titania/Silica Xerogel Dispersions Reinforcing Hydrophilicity and Antimicrobial Resistance of Leathers

Four leather substrates from different animals were treated by dispersions containing hydrophilic composite silica-hyperbranched poly(ethylene imine) xerogels. Antimicrobial activity was introduced by incorporating silver nanoparticles and/or benzalkonium chloride. The gel precursor solutions were also infused before gelation to titanium oxide powders typically employed for induction of self-cleaning properties. The dispersions from these biomimetically premade xerogels integrate environmentally friendly materials with short coating times. Scanning electron microscopy (SEM) provided information on the powder distribution onto the leathers. Substrate and coating composition were estimated by infrared spectroscopy (IR) and energy-dispersive X-ray spectroscopy (EDS). Surface hydrophilicity and water permeability were assessed by water-contact angle experiments. The diffusion of the leather’s initial components and xerogel additives into the water were measured by Ultraviolet-Visible (UV-Vis) spectroscopy. Protection against GRAM- bacteria was tested for Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae against GRAM+ bacteria for Staphylococcus aureus and Enterococcus faecalis and against fungi for Candida albicans. Antibiofilm capacity experiments were performed against Staphylococcus aureus, Klebsiella pneumoniae, Enterococcus faecalis, and Candida albicans. The application of xerogel dispersions proved an adequate and economically feasible alternative to the direct gel formation into the substrate’s pores for the preparation of leathers intended for medical uses

On the development of the 3C-SiC Power Law and its applicability for the Evaluation of Termination Structures

The 3C-Silicon Carbide (SiC) has been investigated as the suitable material for medium rated power device applications. Compared to growing 4H-SiC on hexagonal SiC, growing 3C-SiC on Si wafers is quite cost-effective and has recently resulted in epitaxial layers with thickness capable of supporting voltages of this magnitude. In this work, the power law of 3C-SiC is derived for the first time towards predicting the breakdown voltage of vertical Schottky Barrier Diodes (SBDs) based on this wide bandgap (WBG) semiconductor material. To ensure the predicted blocking capabilities from the 3C-SiC power law expression will be supported to the largest extend in fabricated SBDs, termination topologies are adjusted and investigated by performing extensive Technology Computer Aided Design (TCAD) simulations. A comprehensive map is developed to allow the decision on the termination concept for 3C-SiC-on-Si SBDs to be made based on efficiency and area requirement criteria

A Defects-Based Model on the Barrier Height Behavior in 3C-SiC-on-Si Schottky Barrier Diodes

3C-silicon carbide (3C-SiC) Schottky barrier diodes (SBDs) on silicon (Si) substrates (3C-SiC-on-Si) have been found to suffer from excessive subthreshold current, despite the superior electrical properties of 3C-SiC. In turn, that is one of the factors deterring the commercialization of this technology. The forward current–voltage ( $I$ – $V$ ) characteristics in these devices carry considerable information about the material quality. In this context, an advanced technology computer-aided design (TCAD) model is proposed and validated with measurements obtained from a fabricated and characterized platinum/3C-SiC-on-Si SBD with scope to shed light on the physical carrier transport mechanisms, the impact of traps, and their characteristics on the actual device performance. The model includes defects originating from both the Schottky contact and the heterointerface of 3C-SiC with Si, which allows the investigation of their impact on the magnification of the subthreshold current. Furthermore, the simulation results and measured data allowed for the identification of additional distributions of interfacial states, the effect of which is linked to the observed nonuniformities of the Barrier height value. A comprehensive characterization of the defects affecting the carrier transport mechanisms of the investigated 3C-SiC-on-Si power diode is thus achieved, and the proposed TCAD model is able to accurately predict the device current both during forward and reverse bias conditions

3C-SiC-on-Si MOSFETs: Overcoming Material Technology Limitations

The cubic polytype (3C-) of Silicon Carbide (SiC) is an emerging semiconductor technology for power devices. The featured isotropic material properties along with the Wide Band Gap (WBG) characteristics make it an excellent choice for power Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). It can be grown on Silicon (Si) substrates which is itself advantageous. However, the allowable annealing temperature is limited by the melting temperature of Si. Hence devices making use of 3C-SiC on Si substrate technology suffer from poor or even almost negligible activation of the p-type dopants after ion implantation due to the relatively low allowable annealing temperature. In this paper, a novel process flow for a vertical 3C-SiC-on-Si MOSFET is presented to overcome the difficulties that currently exist in obtaining a p-body region through implantation. The proposed design has been accurately simulated with Technology Computer Aided Design (TCAD) process and device software. To ensure reliable prediction, a previously validated set of material models have been used. Further, a channel mobility physics model was developed and validated against experimental data. The output characteristics of the proposed device demonstrated promising performance, what is potentially the solution needed and a huge step towards the realisation of 3C-SiC-on-Si MOSFETs with commercially grated characteristics